I will be going over how much data a thief has access to if they A) Steal your iPhone and B) Have ur passcode. This may apply to android.
1: The thief can access encrypted password protected note's with locks on them, after resetting (not disabling) TouchID or FaceID to their biometrics, the notes.app will not ask for note password and they can use their own face or finger to unlock it and view it. (the thief has no way of getting the password to the note if its not saved anywhere inside of the note, but they dont need it to access it after this.
2: The thief can view saved passwords in Settings.app after turning off or restting FaceID or TouchID.
3: The thief can reset/change iCloud/AppleID password with just a passcode kicking you off every device you own etc.
4: The thief can use any 3rd party apps that were biometricly tied to you, some apps will require account passwords for serious changes (like amazon.app)
Video I saw before testing: https://youtu.be/QUYODQB_2wQ
dskatter t1_ja7v6pb wrote
Simple solution to all of this: have a long passcode, and never enter it when you’re not in private or can’t cover part of the phone with your hand.
This is such an overblown non-issue.